Rotary piston engine

ABSTRACT

A rotary piston engine comprising at least one rotary piston for compressing and/or expanding a working gas in at least one working chamber and a method for compressing and/or expanding a working gas in a rotary piston engine are provided. The rotary piston engine comprises at least one rotary piston with at least one rotatably mounted rotational body and at least one sealing portion that can be moved relative to the rotational body for sealing the at least one working chamber. In the method for compressing and/or expanding a working gas in a rotary piston engine, the working gas is compressed by a rotary piston in a first working chamber and transferred into a second working chamber in order to be ignited, wherein the working gas is supplied with fuel in the second working chamber and/or is further compressed.

The invention relates to a rotary piston engine comprising at least onerotary piston for compressing and/or expanding a working gas in at leastone working chamber and to a method for compressing and/or expanding aworking gas in a rotary piston engine.

A similar rotary piston engine and a method for compressing and/orexpanding a working gas in a rotary piston engine is known e.g. from DE10 2011 109 966.

Such a rotary piston engine for compressing and expanding a working gascomprises at least one working piston about the rotational axle of whichgenerally several working chambers are formed and rotatable in which theworking gas is compressed, optionally ignited and expanded afterignition, where the working chambers can be arranged in succession inthe axial direction and/or in the circumferential direction of theworking piston. In addition, such a rotary piston engine generallycomprises at least one auxiliary piston with a geometry that iscomplementary to the working piston and rolls in a sealing manner alongthe working piston so that at least one working chamber of variablevolume is formed for compressing and expanding the working gas.

Unlike a reciprocating engine of traditional design, all work cycles(aspiration, compression, ignition, expansion) of the rotary pistonengine are performed during rotation of the rotary piston, without therotary piston changing its direction of motion. Different working cyclescan there also occur simultaneously in different working chambers. Theexplosion energy of the ignited working gas preferably acts directly inthe circumferential direction on the working piston which is alsoresponsible for compressing the working gas. Like in an aircraft gasturbine, the explosion energy of the ignited working gas is thereby useddirectly to drive the compressor and to compress the working gas, sothat in theory, a particularly high degree of efficiency of the rotarypiston engine arises.

However, known problems of rotary piston engines are compressionpressure losses due to relatively long gas courses and sealing problemsof the working chambers in the compression and expansion stage, thermalexpansion of the housing and the rotary pistons, in particular due tothe large friction surfaces and high rotational speeds, the centrifugalforces and the inertia of the working gas having adverse effects on theflow of gas and the mixing of the air-fuel mixture prior to ignition,the oil inlet into the working chambers in the operating or restingstate, controllability of the ignition due to rapidly rotating pistonsin particular at different rotational speeds (change of load). Thisreduces the output and efficiency of the rotary piston engine. For thesereasons, the rotary piston engine has in practice not been able toprevail despite the many advantages over reciprocating piston engines.

The invention is therefore based on the object to improve a known rotarypiston engine of the aforementioned type and a method for its operationsuch that improved output and increased efficiency is achieved.Flexibility in the executability and the adaptability to the most variedsituations and expectations is of significance, in particular to meetthe requirements of a wide variety of applications. In the focus ofdevelopment are, inter alia, the use of different fuels (gasoline,diesel, hydrogen, etc), for externally-supplied ignition and spontaneousignition, controllability and adjustability at least in the same manneras for the reciprocating engine (gas intake, ignition timing, gasoutlet, gas quantity, volumes, ignition chamber, etc.), usability as asynchronous engine e.g. for generators, block heating plant and machinetools, but as well for driving vehicles, vessels or aircrafts. Theconfiguration is to be as simple as possible.

The object of the invention is satisfied by individual solutions(aspects) that already by themselves, but in particular in theirinteraction enable a rotary piston engine and a method for its operationwith improved output and increased efficiency, where the individualsolutions are claimed individually as well as in combination.

According to a first aspect of the invention, the object is satisfied bythe rotary piston engine according to claim 1 for compressing and/orexpanding a working gas in at least one working chamber, comprising atleast one rotary piston with at least one rotatably mounted rotationalbody and at least one sealing portion which can be moved relative to therotational body for sealing the at least one working chamber. Due to thesealing portion being movable relative to the rotational body, sealinggaps between the stationary and the rotating parts of the rotary pistonengine, for example, due to thermal expansion of materials, can in everyoperating mode of the rotary piston engine be better closed and sealed,so that the pressure and fuel losses in the compression and expansionstage are reduced and the output and the efficiency of the rotary pistonengine are improved.

For better understanding of the invention described and claimed, someterms are clarified in advance:

The terms axial, radial and circumferential direction respectivelypertain to the rotational axle of the rotary piston respectively atissue. Axial direction refers to a direction along or parallel to therotational axle of the respective rotary piston. Radial direction,however, refers to a direction perpendicular to said rotational axle.The circumferential direction extends along the circumference of anarbitrary circle whose center is located on the rotational axle.

The first aspect of the invention, as mentioned earlier, relates mainlyto sealing the working chambers between the stationary and the rotatingparts of the rotary piston engine. The term sealing surface in thecontext of this invention refers to the surface of a stationary orrotating part of the rotary piston engine that in a sealing manner facesa corresponding surface of a stationary or rotating part of the rotarypiston engine—the so-called sealing partner—to prevent leakage of theworking gas through the sealing gap between the sealing surfaces. In thepresent case, there are seals between stationary and rotating parts ofthe rotary piston engine (working pistons or auxiliary pistons againstthe housing) as well as seals among rotating parts of the rotary pistonengine relative to each other (working pistons against auxiliarypistons).

It can be advantageous to have the at least one rotary piston fulfillsat least one of the following requirements:

-   -   The rotary piston is rotatable about a rotational axle while        maintaining the seal of the at least one working chamber.    -   At least one rotary piston is a working piston for compressing        and/or expanding a working gas, about the rotational axle of        which the at least one working chamber is formed and/or rotates,        whereby preferably at least two working chambers are disposed in        succession in the axial direction and/or in the circumferential        direction of the working piston.    -   At least one rotary piston is an auxiliary piston having a        geometry that is complementary to the working piston to roll in        a sealing manner against the working piston, preferably to form        a working chamber with a variable volume.

It can also prove useful, however, to have the at least one rotationalbody fulfill at least one of the following requirements:

-   -   The rotational body comprises at least one sealing surface at        least temporarily sealing the at least one working chamber        during the rotating motion, wherein the sealing surface        preferably in the axial direction and/or in the radial direction        and/or in the circumferential direction faces away from the        rotational body.    -   The rotational body comprises at least one recess for forming        the at least one working chamber.    -   The rotational body comprises an adjustable geometry such that        the volume of at least one recess is variable for forming the at        least one working chamber.    -   The rotational body comprises at least two recesses for forming        a respective working chamber, where the recesses are preferably        arranged in succession in the axial direction and/or in the        circumferential direction, where the recesses are of different        dimensions preferably in the axial direction and/or in the        radial direction and/or in the circumferential direction.    -   The rotational body comprises at least one cavity sealed against        the at least one working chamber.

It can also prove practical, however, the have the at least one sealingportion fulfill at least one of the following requirements:

-   -   The sealing portion comprises at least one sealing surface which        preferably in the axial direction and/or in the radial direction        and/or the circumferential direction faces away from the sealing        portion, where the sealing surface is formed preferably as a        rotationally symmetrical surface or as a portion thereof, where        the sealing surface preferably has the shape of a cylinder        jacket and/or a cone jacket and/or a sphere jacket or of a        circular disk or at least a portion thereof.    -   The sealing portion at a sealing surface comprises at least one        preferably line-shaped sealing lip which projects in the        direction of a sealing partner, where the sealing lip preferably        extends in a wave-shaped or sinusoidal manner in the        circumferential direction, where the wave-shaped or sinusoidal        sealing lip travels a phase angle of at least 180° around the        circumference of the rotary piston.    -   The sealing portion is at least in sections disposed at an axial        and/or a radial end of the rotational body, where the sealing        portion preferably encompasses the rotational body preferably in        the axial direction and extends at least in sections along both        axial ends of the rotational body.    -   The sealing portion is reversibly transferable between a first        state, in which a sealing surface of the sealing portion        connects flush to or at a distance from a sealing surface of the        rotational body and/or to a sealing surface of another sealing        portion, and in a second state, in which the sealing surface of        the sealing portion in the direction of a sealing partner        projects beyond the sealing surface of the rotational body        and/or beyond the sealing surface of another sealing portion.    -   The sealing portion is movable relative to the rotational body        along a line in a plane including the rotational axle of the        rotary piston, preferably along or parallel to the rotational        axle of the rotary piston and/or radially and/or at an acute        angle to the rotational axle of the rotary piston.    -   The sealing portion is movable only along a preferably straight        line relative to the rotational body, whereas all the other        motions of the sealing portion relative to the rotational body        are blocked.    -   The sealing portion is movable relative to at least one further        sealing portion and/or to the rotational body while maintaining        the seal of the at least one working chamber.    -   The sealing portion is slidably guided at the rotational body.    -   The sealing portion seals the at least one working chamber in        the axial direction and/or in the radial direction and/or in the        circumferential direction.    -   The sealing portion is resiliently preloaded or preloadable        against the rotational body, where the resilient preload        preferably pushes apart or presses together the sealing portion        and the rotational body.    -   The sealing portion is configured such that it is during        rotation of the rotary piston movable due to the centrifugal        force, where the sealing portion is preferably due to the        centrifugal force spaced from the rotational axle of the rotary        piston.    -   The sealing portion at least at one end, in the direction of        rotation of the rotary piston preferably at a front end,        comprises a bevel to facilitate penetration of the sealing        portion into a complementary geometry of a sealing partner.    -   The sealing portion is substantially a rotationally symmetrical        component or a portion thereof, where the sealing portion is        formed preferably circular-segment-shaped, ring-segment-shaped        or arc-shaped.    -   The sealing portion forms an outer edge of the rotary piston.    -   The sealing portion is in the axial direction and/or in the        radial direction and/or in the circumferential direction fixed        at the rotational body in a form-fit manner.    -   The sealing portion is made of heat-resistant material,        preferably ceramics.    -   The sealing portion is made of ductile material, preferably        copper.    -   The sealing portion is made of porous material.    -   The sealing portion is made of material having the same thermal        expansion coefficient as the housing and/or at least one further        rotary piston.    -   At least two sealing portions are in the axial direction and/or        in the radial direction and/or in the circumferential direction        disposed adjacent and/or in overlap.    -   At least two sealing portions together form a continuous or        enclosed or self-contained seal.    -   At least two sealing portions are movable relative to each other        while maintaining a continuous or closed or self-contained seal.    -   At least two sealing portions are identical or symmetrical or        complementary to each other.    -   At least two sealing portions seal the at least one working        chamber completely in the axial direction and/or in the radial        direction and/or in the circumferential direction.    -   At least two sealing portions are arranged in pairs at opposite        axial ends of the rotational body.    -   At least two sealing portions are resiliently preloaded or        preloadable against each other, where the resilient preload        preferably pushes apart or presses together the sealing        portions.

An improved seal of the working chamber can in every operating state ofthe rotary piston be ensured by a sealing portion configured accordingto at least one of the above features, where the sealing portion can beparticularly well adapted to the characteristics of the respectivesealing partner in terms of materials and contours.

It can also be useful to have the rotary piston engine comprise ahousing fulfilling at least one of the following requirements:

-   -   The housing comprises at least one inlet for introducing working        gas into the working chamber.    -   The housing comprises at least one outlet for discharging        working gas from the working chamber.    -   The housing is at least in part constructed in a        mirror-symmetrical manner, preferably mirror-symmetrical to a        plane which is spanned by the rotational axles of two rotary        pistons.    -   The housing comprises at least two parts, preferably at least        two substantially mirror-symmetrical parts, preferably at least        two identical parts so as to cover the rotary piston on        different sides of its circumference.    -   The housing is split substantially in a plane which is spanned        by the rotational axles of two rotary pistons or in a plane        parallel thereto.

A housing according to the foregoing features is easy to manufacture,compact and easy to assemble and can also again be dismantled in thecase of required access to the rotating components of the rotary pistonengine.

According to a second aspect of the invention, the above-formulatedobject is satisfied by the rotary piston engine according to claim 6,preferably in combination with at least one of the foregoing embodimentsfor compressing and/or expanding a working gas in at least one workingchamber, having a housing and having at least one rotary pistonrotatably mounted in the housing, where the housing comprises at leastone lubricant channel for supplying lubricant to the rotary pistonand/or for removing lubricant from the rotary piston. Force-feedcirculatory lubrication via the lubricant channels can in any operatingstate of the rotary piston engine ensure a better seal of the workingchamber.

In an advantageous embodiment of the invention, the lubricant channelfulfills at least one of the following requirements:

-   -   The lubricant channel removes lubricant from the rotary piston        into a lubricant reservoir.    -   The lubricant channel is configured such that lubricant collects        in the lubricant reservoir.    -   The lubricant channel extends at least in sections preferably in        an arc-shaped manner around the rotary piston and/or around the        working chamber.    -   The lubricant channel is constructed such that the lubricant        adheres to the lubricant channel wall due to adhesion.    -   The lubricant channel is constructed such that the lubricant        drains due to weight force.    -   The lubricant channel at least in sections extends within and/or        outside the housing.    -   The lubricant channel at an apex above the rotary piston has a        smaller radius of curvature than the greatest radius of the        rotary piston, where the lubricant channel below the apex        preferably has a larger radius of curvature than the greatest        radius of the rotary piston.    -   The lubricant channel comprises at least one branching.    -   The lubricant channel comprises at least one lubricant supply        line for supplying lubricant to the rotary piston, preferably at        least to one mounting location of the rotary piston and/or to at        least one sealing surface of the rotary piston.    -   The lubricant channel is part of a lubricant circuit, preferably        of a closed lubricant circuit, where the lubricant removed from        the rotary piston is preferably cleaned and is again supplied to        the rotary piston.

The lubricant channel according to the above features can welldistribute the required lubricant over the contact surfaces to belubricated and reliably drain excess lubricant.

According to a further advantageous embodiment of the invention, thelubricant channel comprises at least one collecting portion forcollecting lubricant from the rotary piston, where the collectingportion fulfils at least one the following requirements:

-   -   The collecting portion opens towards the rotary piston,        preferably towards at least one mounting point of the rotary        piston and/or towards at least one sealing surface of the rotary        piston.    -   The collecting portion extends at least in sections in the        circumferential direction of the rotary piston.    -   The collecting portion is disposed radially outside and axially        within the rotary piston, or radially within and axially outside        the rotary piston.    -   The collecting portion is configured such that it receives        lubricant cast off from the rotary piston due to the centrifugal        force.    -   The collecting portion comprises at least two parallel grooves        which are separated from each other by at least one wall        portion, where the wall portion—when viewed in        cross-section—tapers or widens preferably from a proximal to a        distal end and/or where the wall portion—when viewed in        cross-section—is concave between the proximal end and the distal        end, where the wall portion—when viewed in        cross-section—preferably at the distal end comprises an        arrow-shaped profile, the tip of which faces away from the        proximal end of the wall portion.    -   The collecting portion comprises at least two parallel grooves        which are preferably deeper than wide.    -   The collecting portion comprises a backflow inhibitor which        prevents leakage of the lubricant already collected.    -   The collecting portion is configured to receive lubricant        supplied to the rotary piston by force-feed circulatory        lubrication in the operating state and in the resting state of        the rotary piston engine.

According to a third aspect of the invention, the object formulatedabove is also satisfied by a method for compressing and/or expanding aworking gas in a rotary piston engine, preferably in a rotary pistonengine according to at least one of the preceding embodiments, where theworking gas is compressed by a rotary piston in a first working chamberand transferred into a second working chamber in order to be ignited,characterized in that the working gas is in the second working chambersupplied with fuel and/or is further compressed.

It can be advantageous to have the method comprise at least one of thefollowing steps:

-   -   The compressed working gas is passed through the rotary piston        and/or through the housing of the rotary piston engine,        preferably radially inwardly from the first working chamber into        the second working chamber.    -   Fuel is injected into the second working chamber prior to and/or        during and/or after the further compression.    -   The working gas is in the second working chamber further        compressed by at least one reciprocating piston, where the        reciprocating piston is preferably driven pneumatically and/or        hydraulically and/or mechanically by a cam or eccentric shaft        coupled to the rotary piston motion, where the reciprocating        piston and the rotary piston particularly preferably run at the        same rotational speed.    -   The working gas is introduced already in a compressed state into        the first working chamber, where the compression is effected        preferably by a turbocharger.    -   The working gas is in the second working chamber made to ignite        by being supplied with fuel and/or by further compression.    -   The ignited working gas is passed through the rotary piston        and/or through the housing of the rotary piston engine,        preferably radially outwardly from the second working chamber        into the first working chamber.

The preferred embodiments of the invention are described in detail belowwith reference to the figures.

BRIEF DESCRIPTION OF THE FIGURES

In the drawing:

FIG. 1 shows schematic views of a rotary piston engine according to theinvention; in particular FIG. 1 a shows a perspective view of a rotarypiston engine according to the invention with a housing partially openwhich is split in a plane including the rotational axles of the rotarypistons; FIG. 1 b shows a schematic sectional view of a rotary pistonengine according to the invention for illustrating the interaction ofthe individual components; and FIG. 1 c shows a schematic sectional viewof a modification of the rotary piston engine according to the inventionof FIG. 1 b in which the rotary pistons in the left half of the imagerotate in a phase that is shifted or opposite to the rotary pistons onthe right half of the image to compensate an imbalance caused by thepiston position, where four different work strokes (aspiration,compression, ignition/expansion and discharge) occur simultaneously indifferent working chambers of the rotary piston engine.

FIG. 2 shows schematic views of the rotary piston of a rotary pistonengine according to the invention; in particular FIG. 2 a shows a sideview of the rotary pistons; FIG. 2 b shows the rotary pistons withsealing portions in a front view in a first state in which the sealingsurfaces of the sealing portions and of the rotational body at theauxiliary pistons extend flush with each other; and FIG. 2 c shows theupper auxiliary piston with sealing portions in enlarged detail view andin a front view in a second state in which the sealing surfaces of thesealing portions project at the auxiliary pistons in the axial directionbeyond the sealing surfaces of the rotational body.

FIG. 3 shows schematic views of a rotary piston of the rotary pistonengine according to the invention being configured as a working piston;in particular FIG. 3 a shows the rotary piston with sealing portions inside view in a first state in which sealing surfaces of the sealingportion and the rotational body extend flush with each other; FIG. 3 bshows the rotary piston with sealing portions in a side view in a secondstate in which the sealing surfaces of the sealing portions projectbeyond the sealing surfaces of the rotational body in the radialdirection.

FIG. 4 shows schematic views of a rotary piston of the rotary pistonengine of the invention being configured as a working piston accordingto an advantageous variant; in particular FIG. 4 a shows the workingpiston with sealing portions in a side view and an enlarged side view ofa detail; FIG. 4 b shows the working piston with sealing portions in afront view in a first state in which sealing surfaces of the sealingportion and the rotational body extend flush with each other; FIG. 4 cshows the rotary piston with sealing portions in a front and an enlargedfront view of a detail in a second state in which the sealing surfacesof the sealing portions project beyond the sealing surfaces of therotational body in the radial direction; FIG. 4 d shows a plan view of arotary piston with sealing portions which extend in a wave-shaped mannerin the circumferential direction.

FIG. 5 shows various schematic views of a rotary piston engine accordingto the invention in various work steps; in particular FIG. 5 a shows aschematic sectional view of the rotary piston engine according to theinvention for illustrating the work cycles in a reciprocating pistonsystem or in the expansion stage, respectively (System A); FIG. 5 bshows a schematic front view of the rotary piston engine according tothe invention with an exposed rotary piston; FIG. 5 c shows a schematicsectional view of the rotary piston engine according to the inventionfor illustrating the work cycles in a rotary piston system or in thecompression stage, respectively (System B); and FIGS. 5 d-f showsimplified and reduced views based on FIGS. 5 a-c.

FIG. 6 shows various schematic views of a rotary piston engine accordingto the invention in various work steps; in particular FIG. 6 a shows asimplified schematic sectional view of the rotary piston engineaccording to the invention for illustrating the work cycles in areciprocating piston system or in the expansion stage, respectively(System A); and FIG. 6 b shows a schematic front view of the rotarypiston engine from FIG. 6 a for illustrating the work cycles in a rotarypiston system or in the compression stage, respectively (System B);

FIG. 7 shows various views of a modification of the rotary piston engineaccording to the invention from FIG. 6; where FIGS. 7 a and 7 b aresubstantially based on FIG. 6 a and FIG. 6 b.

FIG. 8 shows schematic views of a rotary piston engine according to theinvention with an internal reciprocating piston system for illustratingvarious drive concepts for the reciprocating piston; in particular FIG.8 a shows a reciprocating piston system with a pneumatic or hydraulicdrive, where the reciprocating piston motion can be decoupled from therotational motion of the working piston; FIG. 8 b shows a reciprocatingpiston system with a crank drive and rod connection to the rotationalaxle of the working piston; and FIG. 8 c shows a reciprocating pistonsystem with a cam drive and two ignition chambers at the end sides.

FIG. 9 shows a schematic sectional view of a rotary piston engineaccording to the invention with an internal reciprocating piston systemwith a cam drive and an ignition chamber at the end side, where thereciprocating piston is driven mechanically by the axle of the workingpiston configured as a camshaft.

FIG. 10 shows schematic views for illustrating a first chronologicalseries of steps of the method according to the invention for compressingand expanding a working gas in the rotary piston engine of the inventionaccording to the eighth embodiment of the invention; in particular FIG.10 a shows the rotary piston when the gas outlet of the ignition chamberis closed, FIG. 10 b shows the reciprocating piston during aspiration ofthe working gas of System B into the ignition chamber and the rotarypiston during aspiration of air into the working chamber of System A;FIG. 10 c shows the rotary piston when the gas inlet of the ignitionchamber is closed and during aspiration of air into the working chamberof System A; and FIG. 10 d shows the reciprocating piston duringcompression of the working gas in the ignition chamber of System B.

FIG. 11 show schematic views illustrating a second chronological seriesconnecting to the first series of steps of the method for compressingand expanding a working gas in the rotary piston engine according to theinvention; in particular FIG. 11 a shows the reciprocating piston whenblocking the gas inlet of the ignition chamber during simultaneousignition by injection or externally-supplied ignition and the rotarypiston when blocking the intake port of the working chamber of System A;FIG. 11 b shows the rotary piston when opening the gas outlet of theignition chamber for draining the working gas into the working chamberand the reciprocating piston during displacement of the residual gasesfrom the ignition chamber and when blocking the gas backflow into theignition chamber to avoid pressure on the piston top side and to relievethe reciprocating system (e.g. via the cam); FIG. 11 c shows the rotarypiston when the gas inlet of the ignition chamber is opened for shockflushing by precompressed air from System A due to the piston shape andduring expansion of the working gas into and in the rotating workingchamber for driving the working axle; and FIG. 11 d shows the rotarypiston 4 when the gas outlet is opened for discharging the combustiongases.

FIG. 12 shows schematic views for illustrating a third chronologicalseries connecting to the second series of steps of the method forcompressing and expanding a working gas in the rotary piston engineaccording to the invention; in particular FIG. 12 a shows the rotarypiston when the gas outlet of the ignition chamber is closed, when thecombustion gases are discharged from the first working chamber andduring aspiration of working air into the second working chamber; FIG.12 b shows the reciprocating piston during aspiration of the working gasinto the ignition chamber; FIG. 12 c shows the rotary piston whenblocking the gas outlet of the first working chamber, when the chamberof the lower auxiliary piston is opened for discharging the residualgases into the housing and when the gas inlet of the ignition chamber isclosed; and FIG. 12 d shows the reciprocating piston during compressionof the working gas.

FIG. 13 shows schematic views of a rotary piston engine of the inventionaccording to an advantageous embodiment; in particular FIG. 13 a shows aschematic perspective partial view of the rotary piston engine accordingto the invention with the housing partially open; FIG. 13 b shows aschematic sectional view of the rotary piston engine of FIG. 13 aaccording to the invention perpendicular to the rotational axles of therotary pistons; FIG. 13 c shows alternative configurations of collectingportions of a lubricant channel for collecting lubricant; FIG. 13 dshows schematic views of the course of the lubricant channel and thecollecting portion about one of the rotary pistons from which thelubricant is to be removed; FIG. 13 e shows a schematic side view of arotary piston formed as an auxiliary piston during rotation, where thelubricant cast off due to centrifugal force is shown schematically bydroplets.

FIG. 14 shows schematic views of a rotary piston engine of the inventionaccording to a further advantageous embodiment; in particular FIG. 14 ashows a schematic sectional view of the rotary piston engine accordingto the invention perpendicular to the rotational axles of the rotarypistons in the intended installation position; and FIG. 14 b shows therotary piston engine of FIG. 14 a in an inclined position in which therotary piston engine is inclined relative to the intended installationposition in an axis parallel to the rotational axles by an angle α/2.

FIG. 15 shows schematic views of a rotary piston engine of the inventionaccording to a further advantageous embodiment of the invention; inparticular FIG. 15 a shows a schematic sectional view of a rotary pistonengine according to the invention perpendicular to the rotational axlesof the rotary pistons; and FIG. 15 b shows a schematic sectional partialview of the rotary piston engine of FIG. 15 a along the rotational axleof the upper auxiliary piston for illustrating the course of thelubricant channel.

FIG. 16 shows schematic views of a rotary piston engine of the inventionaccording to yet a further advantageous embodiment of the invention; inparticular FIG. 16 a shows a schematic perspective partial view of arotary piston engine according to the invention with a housing partiallyopen; FIG. 16 b shows a schematic sectional view of the rotary pistonengine according to the invention perpendicular to the rotational axlesof the rotary pistons; and FIG. 16 c shows a sectional partial view ofthe rotary piston engine of FIG. 16 b along the rotational axle of theupper auxiliary piston for illustrating the course of the lubricantchannel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the framework of the description, like reference numerals are usedfor the same features and, repetition of descriptions is dispensed withto the extent possible.

The rotary piston engine 1 shown in FIG. 1 operates according to themethod principle described above for compressing and expanding a workinggas and comprises a working piston 4 about its rotational axle 40 ofwhich working chambers 2 are formed and can be rotated to compress theworking gas, possibly to ignite it and expand it after ignition. Workingchambers 2 are disposed spaced apart or in succession in the axialdirection and in the circumferential direction of working piston 4.Working piston 4 comprises a rotational body 41 rotatably mounted inhousing 5 having a plurality of movable sealing portions 42 for sealingworking chambers 2 and with two recesses 43 for forming a respectiveworking chamber 2 which are separated by slider 44. Each of the twoauxiliary pistons 3 comprises two rotational bodies 31, 34 mountedjointly rotatably in housing 5 on which movable sealing portions 32, 33,35, 36 are attached for sealing working chambers 2, where rotationalbodies 31, 34 have a rolling geometry adapted to the rolling geometry ofworking piston 4 to perform a rolling motion in a manner sealing workingpiston 4 and housing 5.

The working gas is in a known manner introduced through an inlet (51;cf. FIGS. 8-12.) into working chambers 2 and compressed by rotation ofworking piston 4, possibly ignited and relaxed after ignition in workingchambers 2. For being supplied with fuel and for ignition, the workinggas can also be transferred through a channel (not shown) from thecompression stage to the expansion stage. However, the working gas canalso be ignited in one of the working chambers 2.

Housing 5 comprises a lubricant channel 6 for the supply and removal oflubricant S to or from upper auxiliary piston 3. This lubricant channel6 comprises inter alia collecting portions 60 for collecting lubricantcast off from rotary pistons 3 due to centrifugal force. For force-feedcirculatory lubrication of mounting points and axial sealing surfaces ofrotary piston 3 with lubricant, several lubricant supply lines 65 (FIG.1 a) can run through housing 5. Further details on the lubricant courseshall be described later in connection with FIGS. 13 to 16.

FIG. 2 shows schematic views of rotary pistons 3, 4 of rotary pistonengine 1 of the invention and in particular illustrates the mode ofoperation of sealing portions 32, 33, 35, 36 and 42. As previouslydescribed in connection with FIG. 1, each of the two auxiliary pistons 3of rotary piston engine 1 according to the invention comprises tworotational bodies 31, 34 mounted jointly rotatable in housing 5, wheremovable sealing portions 32, 33, 35, 36 are attached at each rotationalbody 31, 34 for sealing working chambers 2. With these sealing portions32, 33, 35, 36, auxiliary piston 3 can maintain the seal of workingchamber 2 also during rotation about its rotational axle 30 and duringthermally induced material expansions.

Each rotational body 31, 34 also comprises a cavity 37 (FIG. 2 a) sealedagainst working chamber 2 and sealing surfaces 31 a/b/c, 34 a/b/c in theaxial direction, in the radial direction and in the circumferentialdirection facing away from rotational body 31, 34, 41 that temporarilyseal working chamber 2 during the rotational motion of rotational body31, 34.

The two sealing portions 32, 33 at one of the rotational bodies 31 (FIG.1 b, 2 b) are configured symmetrically to each other and are arranged inpairs at opposite axial ends of rotational body 31 where sealingportions 32, 33 interact in a toothed manner and in the circumferentialdirection in a form-fitting manner with the complementary contours ofrotational body 31 and can be moved axially away from rotational body 31and towards rotational body 31 while maintaining a continuous seal.Sealing portions 32, 33 are each resiliently preloadable againstrotational body 31, 34, where the resilient preload pushes away each ofthe sealing portions 32, 33 from rotational body 31. As illustrated inFIG. 2 a in enlarged detail, sealing portion 32 at its axial sealingsurface 32 b comprises a line-shaped sealing lip 32 d which projectstoward working piston 4 and in the circumferential direction extends ina sinusoidal manner. Due to the wave shape, so-called fretting ofsealing portion 32 in sealing partner 4 is prevented, because thesealing lip does not always interact with sealing partners 4 at the sameplace but the point of contact meanders in the radial direction. As aresult, wear of sealing portion 32 as well as abrasion at working piston4 can be reduced. Preferably, all of the sealing portions 32, 33, 35, 36comprise such sealing lips 32 d. Sealing lips 32 d are preferably edges32 b that project beyond the respective sealing surface 32 b, but areintegrally connected to the respective sealing portion 32 and are madeof its material.

The two sealing portions 35, 36 (FIGS. 1 b, 2 b) of the other rotationalbody 34, however, are configured complementary to each other anddisposed in pairs 34 at the opposite axial ends of rotational body 34,where sealing portions 35, 36 interact in a toothed manner and in thecircumferential direction in a form-fitting manner and can be movedaxially apart from each other and against each other while maintaining acontinuous seal. Sealing portions 35, 36 are resiliently preloadedagainst each other, where the resilient preload forces apart sealingportions 35, 36.

Sealing portions 32, 33, 35, 36 comprise various sealing surfaces 32a/b/c, 33 a/b/c, 35 a/b/c, 36 a/b/c that in the axial direction, in theradial direction and in the circumferential direction face away fromrespective sealing portion 32, 33, 35, 36. Sealing surfaces 32 a, in theradial direction facing away from sealing portion 32, 33, 35, 36, 33 a,35 a, 36 a, preferably have the shape of a cylindrical jacket portion,whereas sealing surfaces 32 b, 33 b, 35 b, 36 b in the axial directionfacing away from sealing portion 32, 33, 35, 36 are preferably formed inthe shape of circular or annular segments.

In order to seal working chamber 2 in the axial direction, sealingportions 32, 33, 35, 36 are reversibly transferable between a firststate in which the respective sealing surface 32 b, 33 b, 35 b, 36 b ofsealing portion 32, 33, 35, 36 connects flush to or at a distance froman adjacent sealing surface 31 b, 34 b of rotational body 3, and asecond state in which sealing surface 32 b, 33 b, 35 b, 36 b furtherprojects in the direction of housing 5 or working piston 4 as a sealingpartner beyond sealing surface 31 b, 34 b of rotational body 31, 34.While maintaining the seal of working chamber 2, each sealing portion32, 33, 35, 36 is movable only parallel to the rotational axle 30 ofrotary piston 3 relative to rotational body 31, 34, 41, whereas allother free degrees of motion of sealing portion 32, 33, 35, 36 are withrespect to rotational bodies 31, 34 locked and blocked. The motion ofsealing portion 32, 33, 35, 36 relative to rotational body 31, 34 canthere, for example, compensate enlarged gaps due to a thermally inducedmaterial expansion.

Sealing portions 32, 33, 35, 36 at their—in the direction ofrotation—front end comprise bevels 35 d, 36 d to facilitate penetrationof sealing portion 32, 33, 35, 36 in a respective complementary geometryof working piston 4 as a sealing partner during a rolling motion.

Sealing portions 32, 33, 35, 36, 42 are preferably made of heatresistant material, such as ceramics, of ductile material, such ascopper, or of porous material, where the material of each sealingportion 32, 33, 35, 36 preferably has the same thermal expansioncoefficient as housing 5 and/or working piston 4, so that thermallyinduced material stresses due to different thermal expansioncoefficients can be prevented or at least reduced.

As can be seen in FIG. 3, each rotational body 41 comprises asubstantially cylindrical central portion 4 a and two circulardisk-shaped axial side portions 4 b, at the axial end side of which aplurality of movable sealing portions 42 is attached for sealing workingchambers 2. Sealing portions 42 are substantially formed identical andcircular-segment-shaped, or ring-segment-shaped and arranged in twoaxially adjacent rows, which are offset in the circumferential directionby approximately half a circumferential length of a sealing portion 42,at the outer circumferential edge of working piston 4. Sealing portions42 are thereby arranged adjacent in the circumferential direction andoverlap in the axial direction, where sealing portions 42 on both axialends of rotational body 41 form a continuous axial end seal of workingchamber 2 closed in the circumferential direction. Sealing portions 42are movable relative to each other while maintaining the self-containedseal. With these sealing portions 42, auxiliary piston 4 can maintainthe seal of working chamber 2 also during rotation about its rotationalaxle 40.

Two recesses 43 are disposed in succession radially outside thecylindrical center portion 4 a and axially within the circulardisk-shaped side portions 4 b for forming a respective working chamber 2in the circumferential direction of rotational body 41 and separated byslider 44 (FIG. 3 a/b), where slider 44 has a rolling geometry orevolvent geometry adapted to the rolling geometry of the associatedauxiliary piston (not shown) to perform a rolling motion in a mannersealing the working piston and the housing. The geometry of rotationalbody 41 is adjustable, for example, by varying the axial length or byspacing the two axial side portions 4 b, respectively, such that thevolume of the recesses 43 for forming working chambers 2 can be varied.The geometry of the auxiliary piston is then adapted accordingly.

Rotational body 41 comprises sealing surfaces 41 a/b/c which in theaxial direction (41 b), in the radial direction (41 a), and in thecircumferential direction (41 c) face away from rotational body 41 andwhich seal working chambers 2 formed in recesses 43 toward the outsideduring the rotational motion of rotational body 41. This is inparticular a seal for working piston 4. The individual sealing portions42 are during rotation of working piston 4 due to the centrifugal forcemovable in the radial direction and are with increasing rotational speedincreasingly spaced from the rotational axle 40 of working piston 4.

Sealing portions 42 are resiliently preloaded in the direction ofrotational body 41, where the resilient preload pulls sealing portions42 in the direction of rotational body 41, i.e. opposite to thedeflection effected by the centrifugal force.

As a result, the increase in the degree of efficiency is accomplisheddue to specially shaped working pistons 4 with internal recesses 43 forforming working chambers 2, the centrifugal seal by the radially movablesealing portions 42 at rotational body 41 of working piston 4, and thecomplementarily shaped auxiliary pistons 3 with sealing portions 32, 33,35, 36 at the rotary bodies 31, 34 movable laterally and in the axialdirection. The shape of working piston 4 with working chambers 2 locatedin the piston volume allows a centrifugal seal with possibly resilientlypreloaded sealing portions 42 that seal working piston 4 at both axialends in the circumferential direction in a self-contained manner againsthousing 5. An axial seal against housing 5 is thereby no longerrequired. Several rows of sealing portions 42 offset from each other,due to the larger area as compared to a single row, counteract rapidwear and form a labyrinth seal which lets the working gas escape withmore difficulty, even if sealing portions 42 move in the radialdirection 42 and gaps thereby arise between sealing portions 42 disposedadjacently in the circumferential direction. Working piston 4 is in nolateral contact with housing 5, whereby no frictional heat is generated.In addition, it can expand without getting seized on housing 5.

Auxiliary pistons 3 extending in the interior are mounted with lateralsealing portions 32, 33, 35, 36, so that there is a lateral seal againstworking piston 4. These sealing portions 32, 33, 35, 36 can beresiliently mounted and can also use the centrifugal force when acomponent of motion in the radial direction is possible. Contacting theside wall is effected via sealing portions 32, 33, 35, 36. Rotationalbodies 31, 34 of auxiliary piston 3 can accordingly be shaped in amaterial-saving and light manner.

In an alternative embodiment according to FIG. 4, a respective pluralityof movable sealing portions 42 for sealing working chambers 2 is alsoattached to the outside of the two circular disk-shaped axial sideportions 4 b of working piston 4. Sealing portions 42 are again formedsubstantially identical and circular-segment-shaped orring-segment-shaped but arranged in only one row at the outercircumferential edge of working piston 4. The individual sealingportions 42 are therefore adjacently disposed only in thecircumferential direction and not in the axial direction (FIG. 4 b/c).The two sealing portions 42 that overlap a slider 44 in thecircumferential direction are in the axial direction directly connectedto each other by a connecting member 42 d, where connecting member 42 dinterrupts axial side portions 4 b of working piston 4 and forms theridge of slider 44 in the radial direction (FIG. 4 a) This connectingmember 42 d is with the deflection of sealing portions 42 induced by thecentrifugal force deflected in the radial direction, where the maximumdeflection of sealing portions 42 in the radial direction is restrictedby the maximum possible depth of immersion of slide 44 or connectingmember 42 d, respectively, into the complementary geometry of thesealing partner or auxiliary piston 3, respectively. The deflection ofsealing portions 42 connected via the connecting member 42 d is therebyautomatically regulated, where the maximum deflection can also betransferred to the other sealing sections.

As the detail enlarged in FIG. 4 c shows by way of example, sealingportion 42 can at its axial sealing surface 42 a comprise a line-shapedsealing lip 42 e which extends in the direction of housing 5 and in thecircumferential direction in a sinusoidal manner. As a result, frettingof sealing portion 42 in the sealing partner is also for the radiallymovable centrifugal seal prevented by the wave shape, because the pointof contact of sealing lip 42 e to housing 5 meanders in the axialdirection and therefore does not always pass over the same locations.Consequently, wear of sealing portion 42 and abrasion at housing 5 canbe reduced. Preferably all sealing portions 42 comprise such sealinglips 42 e, where sealing lips 42 e of sealing portions 42 adjacent inthe circumferential direction and/or in the axial direction are adaptedto each other such that a self-contained wave pattern continuous in thecircumferential direction arises. Sealing lips 42 e are formed as edgesfrom material of the respective sealing portion 42 and integrallyconnected thereto so as to project over sealing surface 42 a in thedirection of sealing partner 5. For improving oil adhesion at sealingsurface 42 a, a wave-shaped groove can be formed alternatively or inaddition to sealing lip 42 e which in the latter case can extend inphase or out of phase with sealing lip 42 e. FIG. 4 e shows amodification of working piston 4 according to FIG. 4 d, where therespective sealing portions 42 are themselves formed in a wave-shapedmanner and are in the circumferential direction strung together suchthat a preferably harmonic wave profile arises enclosed about thecircumference of working piston 4.

A variant of the rotary piston engine according to the invention isdescribed below with reference to FIGS. 5 to 12 in which a reciprocatingpiston 71 with counter-cyclical (non-linear) upwardly and downwardlymotion is used for recompression of the working gas compressed byworking piston 4. Reciprocating piston 71 is located in a controlconsole 7 that is adjustable in housing 5 in the circumferentialdirection which is described in a similar form in DE 10 2011 109 966.Control console 7 comprises a cylinder with a reciprocating piston 71oscillating in the cylinder and at the ends of which two ignitionchambers 70 are formed, each of which is filled via an ignition chamberinlet 74 and is again emptied via an ignition chamber outlet 74. Theworking gas contained or generated in ignition chambers 70 is anair-fuel mixture which can be made to explode by self-ignition orexternally-supplied ignition, e.g. a respective spark plug 72. In thecase of self-ignition, spark plug 72 is not required.

Controlling reciprocating piston 71 is effected by a cam shaft orrotational axle 40 of the working piston with a specially shaped cam 75with or without a rod connection, or by a pneumatic or a hydrauliclifting system (FIGS. 8 a-c). The advantages of the embodiment arisefrom the fact that, in contrast to only one auxiliary piston 3, all fourwork cycles are enabled with one revolution and working chamber 2 can beused for flushing ignition chamber 70. Piston 71 can incidentally beused not only as a reciprocating piston 71. It is possible that theworking gas is ignited in ignition chamber 70 by reciprocating piston 71without further compression. In this case, reciprocating piston 71 canalso only serve to adjust the volume of ignition chamber 70 across anumber of ignition processes.

Characteristic of the rotary piston engine equipped with reciprocatingpiston 71 is furthermore the reduced gas routing and the highcompression ratio which is achieved by the synergetic interaction of therotary piston system with the reciprocating piston system, where theadvantages of both systems are combined in a particularly advantageousmanner. It is for further illustration of the method according to theinvention convenient to look at the processes and work steps of the twoSystems A and B, in which:

-   -   System A (FIGS. 5 a/d, 6 a, 7 a, 8-12.) denotes the        reciprocating piston system comprising ignition chamber 70 with        an adjustable cross-section (volume) and a secondary compressor        (reciprocating piston 71), and    -   System B (FIGS. 5 c/f, 6 b, 7 b.) denotes the rotary piston        system comprising the rotating gas loading unit for pressurizing        ignition chamber 70 with working gas in the gas flow direction.

The advantages of the reciprocating piston system, in particular of thecamshaft, are to be seen in that

-   -   ignition chamber 70 can remain closed longer by reciprocating        piston 71 than in a continuous up and down motion of a normal        crankshaft, so that unintended volume expansion, or having the        working gas run back, respectively, is prevented;    -   gas inlets 73 of ignition chamber 70 can be and remain closed so        that better control can be obtained;    -   the combustion pressure is effected laterally and does not act        upon reciprocating piston 71, where reciprocating piston 71 is        supported by the cylinder wall relieving the lifting system and        the drive shaft; and    -   a slow or fast motion, for example, for compressing or closing        can be enabled by the shape of cam 75.

Cam 75 can be resiliently mounted for the controlled motion in thedirection of the axle or be guided via a mechanism. The illustrationsare merely to be understood by way of example for illustrating theprinciple, but alternative reciprocating piston control is alsopossible.

Cam 75 controls the reciprocating piston 71 preferably such that the gasin the cylinder (or in the ignition chamber 70 of the reciprocatingpiston compression system) is compressed and then displaced therefrom,where reciprocating piston 71 remains in the top position until fullexpansion in the working rotary pistons 4 has been achieved.

To optimize combustion performance, the cross-section of the ignitionchamber is adjustable preferably manually, for example, by using ascrewdriver. The reciprocating piston compression system according tothe invention is not restricted to a rotary piston engine. Filling thecylinder can be performed, for instance, by a Wankel engine. Thereciprocating piston system can also be used for pre-compression of aworking gas for a subsequent thermodynamic process in a rotary pistonengine.

Forming the mixture externally (the fuel is admixed outside of ignitionchamber 70) may not be useful in rotary piston engines due to complexgas routing. Forming the mixture internally (the fuel is admixed withinignition chamber 70) is therefore preferred.

It is in the reciprocating piston system according to the invention, forexample, not necessary to use also an auxiliary rotary piston 3 inaddition to the working rotary piston 4 for active compression of theworking gas by the rotating components. Working gas can be activelyaspired into the ignition chamber alone due to the downward motion ofpiston 70 and be compressed by the subsequent upward motion of piston70.

Of particular significance with regard to the seal of working chamber 2of the rotary piston engine according to the invention is theconfiguration of working rotary piston 4. Since the working rotarypiston according to the invention comprises side parts 4 b defining aworking chamber 2 in the axial direction of working rotary piston 4 onboth sides, only a radial seal of working chamber 2 against housing 5 isstill required. Since working chamber 2 is already defined by the axialside parts 4 b of working rotary piston 4, a seal against stationaryhousing components is omitted in these places. For the reason thatsealing lips are in this case to have a sealing configuration only inone direction, complex structures can be largely avoided. In addition toless development heat and frictional heat within the rotary pistonengine according to the invention, this results in long-term advantagessuch as reduced wear. Since both the working rotary piston 4 as well asits associated auxiliary rotary piston 3 have substantially the samecircumferential speeds, far lower relative speeds occur between therotating components than between rotating and stationary components.

The method according to the invention for compressing and expanding aworking gas being described below with reference to FIGS. 5 to 12provides that the working gas is compressed by working piston 4 in thefirst working chamber 2 and is for ignition transferred into the secondworking chamber or ignition chamber 70, respectively, where the workinggas is in the second working chamber or ignition chamber 70,respectively, supplied with fuel and/or further compressed.

Working gas, for example, air is there introduced into the first workingchamber 2 in an uncompressed state or already in a compressed state.Compression of the working gas prior to the introduction into the firstworking chamber 2 can be done, for example, by a turbocharger. Theworking gas is in the first working chamber 2 compressed by the rotationof working piston 4. Fuel can be injected into the second workingchamber or into ignition chamber 70 prior to and/or during and/or afterfurther compression. The working gas is further compressed in the secondworking chamber or ignition chamber 70, respectively, by reciprocatingpiston 71, where reciprocating piston 71 can—as previously explained—bedriven pneumatically, hydraulically or mechanically. Alternative driveconcepts for reciprocating piston 71 are shown schematically in FIGS. 8a to 8 c, as well as in FIG. 9. In a pneumatic or hydraulicreciprocating piston drive, the motion of the reciprocating piston canbe decoupled from the motion of the rotary piston. When thereciprocating piston, however, is driven mechanically by a cam or aneccentric shaft coupled to the motion of the rotary piston,reciprocating piston 71 and rotary piston 4 preferably run at the samerotational speed. This allows the work cycles in the first and secondworking chamber 2, 70 to be better coordinated.

FIGS. 5 e to 5 f schematically illustrate the processes in both SystemsA and B, where the following method steps are passed in a total of 4cycles with two ignitions per revolution:

System B:

-   {circle around (1)} aspiration of the working gas through gas inlet    51 into working chamber 2;-   {circle around (2)} precompressing the working gas in working    chamber 2 by rotation of working piston 4;-   {circle around (3)} filling ignition chamber 70;

System A:

-   {circle around (4)} aspiration of the working gas through ignition    chamber inlet 73 into ignition chamber 70 by lowering the    reciprocating piston 71 and increasing the volume of ignition    chamber 70;-   {circle around (5)} compressing the gas mixture in ignition chamber    70 by an upwardly motion of reciprocating piston 71 and reducing the    volume of ignition chamber 70 (mixture formed externally), possibly    in combination with injecting fuel into ignition chamber 70 (mixture    formed internally);-   {circle around (6)} ignition of the air-fuel mixture (self-ignition    or externally-supplied ignition by spark plug 72);-   {circle around (7)} combustion and expansion of the working gas from    ignition chamber 70 through ignition chamber outlet into working    chamber 2; and-   {circle around (8)} discharging the exhaust gases from working    chamber 2;    System B (when using a turbocharger)-   {circle around (9)} use of exhaust gases by System A

FIGS. 6 a and 6 b illustrate the working cycles in the reciprocatingpiston system (System A) and in the rotary piston system (System B). Therecompression in System A is effected via a reciprocating piston 71oscillating in ignition chamber 70, where the mixture is formedinternally by fuel injection into ignition chamber 70. Withself-ignition of the air-fuel mixture, the mixture is compressed untilit reaches the ignition point or fuel is injected into the compressedworking gas or an already compressed air-fuel mixture until the ignitionpoint has been reached. Externally-supplied ignition of the air-fuelmixture is effected by spark plug 72.

In System B, gas losses during aspiration of the air due to the leakagethrough the seals are accepted. The gas loading unit is accordinglydesigned to aspire and precompress a larger quantity of air. Theprecompressed quantity of air is used to pressurize the ignitionchamber.

The compression pressure can be adjust and influenced in that, forexample, in System A, the volume of ignition chamber 70 is changed byreciprocating piston 71 and/or in System B, the volume of workingchamber 2 is changed by coaxial displacement of the side parts (4 b) ofworking piston 4 or by replacing working piston 4, in particular whenrotational body 41 of working piston 4 is not formed integrally with theaxle.

FIGS. 10 to 12 schematically show views to illustrate a chronologicalsequence of steps of the method according to the invention forcompressing and expanding a working gas in the rotary piston engineaccording to the invention.

The process has the particular advantage that large quantities of aircan be aspirated in the working chamber formed by the rotary piston andalready be strongly compressed without any reduction in effectivenessdue to fuel leakage arising. The fuel can then be supplied to thealready compressed working gas in the closed volume of the secondworking chamber, so that the risk of fuel leakage is reduced.Self-ignition can thus be realized when the working gas is in the secondworking chamber made to ignite by being supplied fuel and/or by beingfurther compressed. The subsequent compression in the second workingchamber ensures thorough mixing of the air-fuel mixture. Alternatively,the air-fuel mixture can be ignited by a spark plug.

In order to increase the degree of efficiency of the rotary pistonengine according to the invention, further effective measures can betaken in the area of the lubrication arrangement which is describedbelow with reference to FIGS. 13 to 16.

In an advantageous embodiment according to FIG. 13, lubricant channel 6is adapted to deliver lubricant S to upper and lower auxiliary pistons 3and to remove it from there to a lubricant reservoir. Lubricant channel6, as shown in FIGS. 13 a/b/d, there in sections extends around upper(and lower) auxiliary piston 3 and around working chamber 2. Lubricantchannel 6 is constructed such that the lubricant S cast off due to thecentrifugal force (FIG. 13 e) from upper and lower auxiliary piston 3due to adhesion first adheres to the lubricant channel wall and Is thendue to the weight force removed into the collection reservoir (notshown) at the bottom of rotary piston engine 1. Lubricant channel 6 canthere in sections run within and in sections outside housing 5.

A collecting portion 60 for collecting lubricant S cast off due to thecentrifugal force extends radially outside and axially within upper andlower auxiliary piston 3 in the circumferential direction and opens tothe jacket surface of upper and lower auxiliary piston 3. Collectingportion 60, for example, comprises a plurality of parallel grooves 61,each separated by a wall portion 62 and preferably being deeper thanwide. Exemplary alternative embodiments of such collecting portions 60are illustrated in FIG. 13 c in cross-section in a plane intersectingrotational axles 30, 40 of rotary pistons 3, 4. A backflow inhibitor canbe accomplished by design measures in the collecting portion 60, inparticular at upper auxiliary piston 3, and prevent backflow of thepreviously collected lubricant S from collecting portion 60. Forexample, wall sections 62 of collecting portion 60 are at their distalend formed having roughly an arrow shape, where the arrowhead faces awayfrom the proximal end. Lubricant S cast off due to the centrifugal forceby rotary piston 3 penetrates through the gaps between wall portions 62into grooves 61 and due to the arrowheads encounters low resistance.Backflow of lubricant S from collecting portion 60 is prevented firstlyby the fact that lubricant S due to adhesion adheres to the wall of thelubricant channel, and secondly by the fact that lubricant S clings tothe fanned out arrow-shaped ends of wall sections 62 and therefore cannot drip back onto auxiliary piston 3 located directly beneath.Lubricant S flows downwardly in lubricant channel 6 along the channelwall due to weight force and is removed in the direction of thecollection reservoir and is collected there.

FIG. 13 d shows schematic views of the course of lubricant channel 6 andof collecting portion 60 in relation to upper auxiliary piston 3. At anapex 63 of lubricant channel 6, which is preferably located above upperauxiliary piston 3 in a plane enclosing rotational axles 30, 40 ofrotary pistons 3, 4, the radius of curvature of lubricant channel 6 canbe smaller than the largest radius of upper auxiliary piston 3. Draininglubricant S in lubricant channel 6 in the direction of the collectionreservoir can due to this geometry be aided by the influence of weightforce. Below apex 63, the radius of curvature of lubricant channel 6,however, is preferably greater than the largest radius of upperauxiliary piston 3. Alternatively, lubricant channel 6 can both at apex63 as well as also therebelow comprise a larger radius of curvature thanthe largest radius of the upper auxiliary piston.

FIG. 14 a shows a schematic sectional view of a further advantageousembodiment of the rotary piston engine according to the inventionperpendicular to the rotational axles of rotary pistons 3, 4 in theintended installation position and FIG. 14 b shows rotary piston engine1 of FIG. 4 in an inclined position in which rotary piston engine 1 isinclined relative to the intended installation position in an axisparallel to the rotational axles by an angle α/2. Backflow of lubricantS received in lubricant channel 6 in particular to upper auxiliarypiston 3 is stopped by restricting portions 66 which at least insections extend in the circumferential direction of upper auxiliarypiston 3. Oil collecting areas are provided radially outwardly of borderportions 66 that allow tilting and canting of rotary piston engine 1without the oil flowing back to auxiliary piston 3. Restricting portions66 and oil guide paths can there be designed such that rotary pistonengine 1 can even be operated in a “lying” position when the axles ofauxiliary piston 3 and working piston 4 are arranged substantially in ahorizontal plane.

In a further advantageous embodiment shown in FIG. 15, lubricant channel6 comprises several lubricant supply lines 65 a running through housing5 for force-feed circulatory lubrication of mounting points 38 and theaxial sealing surfaces of rotary piston 3 with lubricant S. Lubricantsupply lines 65 a distribute lubricant S across the axial sealingsurfaces of rotary piston 3. Lubricant S flowing off the axial sealingsurfaces of rotary piston 3 is collected in channel portions 65 bextending arc-shaped radially within and axially outside upper auxiliarypiston 3 and above mounting points 38 and supplied to mounting points 38of rotary piston 3. Lubricant S flowing off mounting points 38 of rotarypiston 3 is collected in channel portions 65 c extending arc-shapedradially within and axially outside upper auxiliary piston 3 and belowmounting points 38. Excess lubricant S is discharged directly vialubricant channel 6, into which arc-shaped channel sections 65 b, 65 clead via branches 64, into the collection reservoir, is possiblyfiltered and again supplied via lubricant supply lines 65. Thisaccomplished a self-contained lubricating circuit.

In yet another advantageous embodiment shown in FIG. 16, the lubricantcan be delivered from the axial sealing surfaces of rotary piston 3 viaupper channel portions 65 b directly into lubricant channel 6 withoutthe detour via the mounting points 38 of rotary piston 3. It can therebybe ensured that only unused lubricant reaches mounting points 38 ofrotating piston 3. Channel portions 65 b, 65 c are configured such thatlubricant S drains under the influence of weight force from the axialsealing surfaces and mounting points 38 of rotary piston 3 into channelsections 65 b, 65 c and from there via branchings 64 into lubricantchannel 6 and ultimately reaches the collection reservoir. Although theembodiments of the invention have been described individually, thefeatures disclosed within the context of the embodiments of theinvention can also be used in combination with each other.

Advantages of the Invention

In summary, the invention discloses various advantageous solutions andembodiments for rotary piston engines 1 and pumps.

In an advantageous embodiment of the invention, the rotary piston engineaccording to the invention comprises an auxiliary piston 3 with sealingparts or sealing portions 32, 33, 35, 36 for sealing auxiliary piston 3against working chambers 2 of working piston 4. This embodiment followsthe basic principle that two arc-shaped sealing portions 32, 33, 35, 36mounted laterally o or in rotary body 31, 34 of auxiliary piston 3 areby spring pressure pressed outwardly onto the respective sealing partneror housing 5 or working piston 4, respectively. The jagged shape is toprevent twisting of sealing portions 32, 33, 35, 36 relative to rotatingbodies 31, 34 of auxiliary piston 3 and to reduce slippage of the gas.In addition, sealing portions 32, 33, 35, 36 provide for a smallerfrictional surface against housing 5 and working piston 4. Lateralsealing portions 32, 33, 35, 36 can additionally be lubricated byforce-feed circulatory lubrication.

In a further advantageous embodiment of the invention, the rotary pistonengine according to the invention comprises a working piston 4 withsealing points or sealing portions 42 for lateral sealing of workingchamber 2 against housing 5. This embodiment is based on the basicprinciple that arc-shaped sealing portions 42 movably mounted laterallyon or in rotary body 41 of working piston 4 are, when working piston 4rotates, by the centrifugal force being oppositely to a resilientpreload pressed radially outwardly onto housing 5 or auxiliary piston 3.The jagged shape of sealing portions 42, 41, is again to preventtwisting relative to rotary body 41 of working piston 4 and to reduceslippage of the gas. When sealing portions 42 are arranged overlappingin several rows, the gaps in the spaces arising during radial deflectionof sealing portions 42 can be covered and closed by overlapping sealingportions 42, so that even less pressure losses arise.

In a further advantageous embodiment of the invention, sealing portions32, 33, 35, 36, 42 are preferably made of materials offering less wearor better gliding properties than the respective rotary pistons 3, 4,for example, copper, ceramics, etc. Sealing portions 32, 33, 35, 36, 42are preferably mounted or formed only at the outer edge of rotationalbodies 31, 34, 41 in order to better seal working chambers 2.Alternatively or additionally, sealing portions 32, 33, 35, 36, 42 canalso cover a jacket surface and/or at least one axial end side ofrotational bodies 31, 34, 41 so that, for example, a kind of heat shieldagainst working chamber 2 is formed. In this case, ceramics are suitablematerial. Another option is to bevel the—in the direction ofrotation—front ends of sealing portions 32, 33, 35, 36, 42, i.e. wherefor instance the male and female rolling geometries of auxiliary piston3 and of working piston 4 meet, so that male rotary piston 3, 4 does notimpact the edge of female rotary piston 3, 4 when material expands. Thisresults in the advantage of a better seal against the side walls ofworking chambers 2 also when material expands. Sealing portions 32, 33,35, 36, 42 can also be replaced in an easier and more inexpensive mannerthan rotary pistons 3, 4. Rotary pistons 3, 4 can be configured narrowerand be more flexibly adapted to certain conditions supplementing sealingportions 32, 33, 35, 36, 42.

In yet another advantageous embodiment of the invention, housing 5 ofthe rotary piston engine according to the invention is designed not onlyfor receiving rotary pistons 3, 4, but in particular also for collectingand draining lubricants S from rotary pistons 3, 4 into a collectiongroove or an oil pan. The invention there makes use of the centrifugalforce of rotating rotary pistons 3, 4 in order to cast off and collectlubricants exiting on rotary piston, 3, 4, for example, oil of theforce-feed circulatory lubrication, and to drain them via lubricantchannel 6 in the housing behind working piston 4, at least in sectionsaround working piston 4, or via drain lines outside housing 5 into theoil pan. A collecting portion 60 provided with collecting grooves 61 orslits there collects oil running or dripping down in housing 5 in thearea of auxiliary piston 3 and delivers it via lubricant channel 6 tothe oil pan. Working piston 4 is thereby less contaminated with oilresidues and working chambers 2 are in the compression and expansionstage protected from flooding with oil (cf. oil pressure surge withreciprocating pistons). In particular with the force-feed circulatorylubrication provided, higher pressures and larger quantities of oil arepossible allowing for more consistent and reliable lubrication at highrotational speeds.

Collecting portion 60 with the oil collecting grooves 61 in the circulararc area of the housing portion for receiving auxiliary piston 3facilitates adhesion of the oil by adhesion force and drains the oilsprayed onto the housing wall in a controlled manner along the housingwall into the collection reservoir. An efficient oil drainage system isthereby accomplished. Collection strips and/or depressions in thelateral region of auxiliary piston 3 disposed above working piston 4drain oil running or dripping down (e.g. of the sliding bearing) andforward it into the collection reservoir. Working piston 4 is alsothereby less contaminated with oil residues and working chambers 2 arein the compression and expansion stage protected from flooding with oil.Excess oil is in a reciprocating piston engine the cause for so-calledoil pressure surge and for bad combustion. Higher pressures and largerquantities of oil are possible with force-feed circulatory lubricationallowing for more consistent and reliable lubrication at high rotationalspeeds. Since auxiliary piston 3 does not contact housing 5 disposedabove, no lubrication is required. This results in fewer problems withfriction, thermal expansion and fit. Lubricant channel 6 is adapted todrain dripping oil in the resting state as well as in the operatingstate in a controlled manner and to create a larger collection area forthe oil that is cast off.

Further preferred embodiments of the invention arise from anycombination of the features described in the embodiments.

All embodiments and features disclosed herein can be combined with oneanother. The teaching of the invention is applicable in particularregardless of the shape and number of working and auxiliary pistons.

LIST OF REFERENCE NUMERALS

-   1 rotary piston engine-   2 working chamber-   3 auxiliary piston-   4 working piston-   5 housing-   6 lubricant channel-   7 control console-   30 rotational axle—auxiliary piston-   31, 34 rotational body—auxiliary piston-   31 a, 34 a axial sealing surfaces—auxiliary piston-   31 b, 34 b radial sealing surfaces—auxiliary piston-   31 c, 34 c sealing surfaces in the circumferential    direction—auxiliary piston-   32, 33 sealing portions—auxiliary piston-   32 a, 33 a radial sealing surfaces—sealing portion auxiliary piston-   32 b, 33 b axial sealing surfaces—sealing portion auxiliary piston-   32 c, 33 c sealing surfaces in the circumferential direction—sealing    portion auxiliary piston-   32 d sealing lip—sealing portion auxiliary piston-   35, 36 sealing portions—auxiliary piston-   35 a, 36 a radial sealing surfaces—sealing portion auxiliary piston-   35 b, 36 b axial sealing surfaces—sealing portion auxiliary piston-   35 c, 36 c sealing surfaces in the circumferential direction—sealing    portion auxiliary piston-   35 d, 36 d bevels—sealing portion auxiliary piston-   37 cavity—auxiliary piston-   40 rotational axle—working piston-   41 rotational body—working piston-   41 a radial sealing surfaces—working piston-   41 b axial sealing surfaces—working piston-   41 c sealing surfaces in then circumferential direction—working    piston-   42 sealing portions—working piston-   42 a radial sealing surfaces—sealing portion working piston-   42 b axial sealing surfaces—sealing portion working piston-   42 c sealing surfaces in the circumferential direction—sealing    portion working piston-   42 d connecting portion—sealing portion working piston-   42 e sealing lip—sealing portion working piston-   43 recess—working piston-   44 slider—working piston-   51 gas inlet—housing-   52 gas outlet—housing-   60 collecting portion—lubricant channel-   61 groove—lubricant channel-   62 wall portions—lubricant channel-   63 apex—lubricant channel-   64 branching—lubricant channel-   65 lubricant supply line—lubricant channel-   65 a channel portions—lubricant channel-   65 b channel portions—lubricant channel-   65 c channel portions—lubricant channel-   66 restricting portion—lubricant channel-   70 ignition chamber-   71 reciprocating piston or adjustable piston-   72 spark plug or injector-   73 inlet ignition chamber-   74 outlet ignition chamber-   75 eccentric/cam

1-10. (canceled)
 11. A rotary piston engine for compressing and/orexpanding a working gas in at least one working chamber comprising atleast one rotary piston with at least one rotatably mounted rotationalbody and at least one sealing portion that can be moved relative to theat least one rotational body for sealing the at least one workingchamber, wherein at least two sealing portions together form acontinuous seal and are movable relative to each other while maintaininga continuous seal.
 12. The rotary piston engine according to claim 11wherein the at least one rotary piston comprises at least one recess forforming the at least one working chamber.
 13. The rotary piston engineaccording to claim 11 wherein the at least one sealing portion isconfigured such that, during rotation of the at least one rotary piston,the at least one sealing portion is movable due to the centrifugalforce, and wherein the at least one sealing portion is due to thecentrifugal force spaced from a rotational axle of the at least onerotary piston.
 14. The rotary piston engine according to claim 11wherein at least two sealing portions are in an axial direction and/orin a radial direction and/or in a circumferential direction disposedadjacent and/or overlap each other.
 15. The rotary piston engineaccording to claim 11 wherein at least two sealing portions togetherform an enclosed or self-contained seal.
 16. The rotary piston engineaccording to claim 11 wherein at least two sealing portions are movablerelative to each other while maintaining a closed or self-containedseal.
 17. The rotary piston engine according to claim 11 wherein atleast two sealing portions are identical or symmetrical or complementaryto each other.
 18. The rotary piston engine according to claim 11wherein at least two sealing portions seal the at least one workingchamber completely in an axial direction and/or in a radial directionand/or in a circumferential direction.
 19. The rotary piston engineaccording to claim 11 wherein at least two sealing portions are arrangedin pairs at opposite axial ends of the at least one rotational body. 20.The rotary piston engine according to claim 11 wherein at least twosealing portions are resiliently preloaded or preloadable against eachother, and wherein the resilient preload is configured to push apart orpress together the sealing portions.
 21. A method for compressing and/orexpanding a working gas in a rotary piston engine, the methodcomprising: compressing the working gas by a rotary piston in a firstworking chamber; and transferring the working gas into a second workingchamber in order to be ignited; wherein the working gas is in the secondworking chamber supplied with fuel and/or is further compressed.
 22. Themethod according to claim 21, wherein the method comprises at least oneof the following: a) the compressed working gas is passed through therotary piston and/or through a housing of the rotary piston engine; b)the fuel is injected into the second working chamber prior to and/orduring and/or after the further compression; c) the working gas is inthe second working chamber further compressed by at least onereciprocating piston, wherein the reciprocating piston is drivenpneumatically and/or hydraulically and/or mechanically by a cam oreccentric shaft coupled to the rotary piston motion, wherein the atleast one reciprocating piston and the rotary piston run at the samerotational speed; d) the working gas is introduced already in acompressed state into the first working chamber, wherein the compressionis effected by a turbocharger; e) the working gas is in the secondworking chamber made to ignite by being supplied with fuel and/or byfurther compression; f) the ignited working gas is passed through therotary piston and/or through the housing of the rotary piston engine,radially outwardly from the second working chamber into the firstworking chamber.